Flow cytometry/cell sorting is a critical resource for contemporary research in immunology and cell biology. All projects within this program, and Core 3, have extensive needs for this technology including, in some cases, needs for the same application and reagents. In view of this, we have integrated these needs in Core A to accomplish economy of scale. Core A will provide for flow cytometry and cell sorting needs of program participants. This will include high rate cell sorting based on up to seven parameters (light scatter and fluorescence) and rare event analysis. The facility will also provide up to nine parameter analysis of cell surface marker expression (immunofluorescence) and various static cell physiologic parameters (apoptosis, cell viability, and cell cycle), as well as real-time cell physiologic changes (calcium mobilization, intracellular translocation and mitochondrial membrane potential, etc.) with gating on additional parameters. Services will be provided using the seven facility instruments that currently constitute the National Jewish Medical and Research Center institutional flow cytometry facility.